Mark Cuban has lived in the same house for 18 years

The "Shark Tank" star and owner of the Dallas Mavericks has always been careful with his money.

When Cuban was younger, "I did things like having five roommates and living off of macaroni and cheese, and I was very, very frugal," he tells Money. "I had the worst possible car — those types of things."

Tony Hsieh lives in a trailer park

"Right now I live in an Airstream," he tells Guy Raz on an episode of NPR's "How I Built This" podcast. "I just love it because there's so many random, amazing things that happen around the campfire at night. I think of it as the world's largest living room."

The multi-millionaire says that he prioritizes spending on experiences over things. Plus, his housing choice enhances his creativity, he says.

Sara Blakely finds ways to cut costs wherever she can

When launching Spanx, which would become a billion-dollar business, Sara Blakely kept things lean. "I only spent what I absolutely needed to," the entrepreneur tells Money. "The Spanx headquarters was my 1,100-square-foot apartment. I used my roommate's bedroom."

Even when her company started to take off and she had the money to upgrade, Blakely stayed in the same apartment: "For two additional years, that was the headquarters. Then, from there on out, my headquarters were always way below what I could have spent."

"I have that mentality on everything," the billionaire continues. "If I can save money here or there, I'll do it. [Instead of] a very expensive photographer for $5,000 or whatever, I'm gonna go and get a friend and a camera, and we're going to shoot the pictures ourselves."